Fixes modifier handling for repeat keys.

ui/keyboard/resources/elements/kb-modifier-key.html

 <!--
   -- Copyright 2013 The Chromium Authors. All rights reserved.
   -- Use of this source code is governed by a BSD-style license that can be
   -- found in the LICENSE file.
   -->
 
 <polymer-element name="kb-modifier-key" class="unlocked dark" extends="kb-key">
   <script>
     (function () {
 
@@ skipping 46 matching lines @@
 
         /**
          * Returns whether the modifier for this key is active.
          * @return {boolean}
          */
         isActive: function() {
           return this.state != KEY_STATES.UNLOCKED;
         },
 
         /**
-         * Notifies key that a non-control keyed up.
+         * Notifies key that a non-control keyed was typed.
          * A control key is defined as one of shift, control or alt.
          */
-        onNonControlKeyUp: function() {
+        onNonControlKeyTyped: function() {
            switch(this.state) {
              case (KEY_STATES.TAPPED):
                this.state = KEY_STATES.UNLOCKED;
                break;
            }
         },
 
         populateDetails: function(caller) {
           var detail = this.super([caller]);
           if (this.state != KEY_STATES.UNLOCKED)
@@ skipping 18 matching lines @@
           return states[this.innerText];
         },
 
         set state(value) {
           states[this.innerText] = value;
         }
       });
     })();
   </script>
 </polymer-element>